aos/uuid_collision_test.cc

#include <set>
#include <unordered_set>

#include "glog/logging.h"
#include "gtest/gtest.h"

#include "aos/uuid.h"

namespace aos {
namespace testing {

// Tests that modest numbers of UUID::Random() calls cannot create UUID
// collisions (to test that we have not *completely* messed up the random number
// generation).
TEST(UUIDTest, CollisionTest) {
  std::set<UUID> uuids;
  // When we only had ~32 bits of randomness in our UUIDs, we could generate
  // issues with only ~sqrt(2 ** 32) (aka 2 ** 16) UUIDs.
  // Just go up to 2 ** 22, since too much longer just makes this test take
  // obnoxiously long.
  for (size_t ii = 0; ii < (1UL << 22); ++ii) {
    UUID uuid = UUID::Random();
    ASSERT_FALSE(uuids.count(uuid) > 0) << ii;
    uuids.insert(uuid);
  }
}
}  // namespace testing
}  // namespace aos